Coupler assembly for catheters

ABSTRACT

Coupler assemblies and methods are disclosed as the coupler assemblies may be used with a catheter. An exemplary coupler assembly includes a spherical linkage coupler for a catheter. The coupler comprises a first cylinder portion for connecting to a structure, and a second cylinder portion for connecting to a distal end of a body of the catheter. The coupler also comprises a spherical linkage including at least two link arms. Each of the two link arms are connected on one end to the first cylinder portion and on the other end to the second cylinder portion. The two link arms connect a portion of the structure to the distal end of the catheter and enable the structure to move relative to the distal end of the catheter in response to an external force exerted on the structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. provisionalapplication No. 61/142,079 filed 31 Dec. 2008 (the '079 application) andinternational patent application number PCT/US09/69857 (the '857application) filed 30 Dec. 2009. This application is also acontinuation-in-part of U.S. non-provisional application Ser. No.11/941,073, filed 15 Nov. 2007 (the '073 application), which in turnclaims the benefit of U.S. provisional application No. 60/915,387, filed1 May 2007 (the '387 application). The entire contents of each of the'079, the '073, the '857 and the '387 applications are herebyincorporated by reference as though fully set forth herein.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention relates to a coupler assembly for catheters havingforce-sensing capabilities. The instant invention includes a mechanicalcoupler for coupling a catheter shaft and distal tip sensing components.Such a system may be used with catheters for visualization, mapping,ablation, and/or other methods of diagnosis and treatment of tissue. Theinstant invention also relates to a method for using a mechanicalcoupler to couple a catheter shaft and distal tip components, formedical or non-medical purposes.

b. Background Art

The visualization and treatment of organs and tissues has been advancedthrough the increasing use of catheter systems. Catheter systems havebeen designed for the incorporation of various components to treat anddiagnose ailments, as accomplished through the mapping of organs,sensing of thermal and electrical changes exhibited by a tissue (e.g.,heart), as well as the application of energizing sources (such asradiofrequency, cryogenics, laser, and high frequency ultrasound) totissue.

Catheter systems generally include a portion that contacts the tissue ororgan, or is inserted in an environment (e.g., heart chamber or vessel)to detect a number of parameters, such as for example, location of thetissue, contact or pressure exerted on the tissue, electrophysiologicalattributes of the tissue, or other type of parameters that aid in theevaluation or treatment of the organ or tissue.

It is known that sufficient contact between a catheter, in particular anelectrode provided in connection with a catheter, and tissue during aprocedure is generally necessary to ensure that the procedures areeffective and safe. Current techniques of mapping, visualization andtreatment using energizing sources, such as the use of radiofrequencyenergy during ablation, rely on placing of the electrode (or anothercomponent) of a catheter system in consistent mechanical contact withtargeted tissue. Perforation of the cardiac wall as well as lesionformation (such as lesions created by exposure to radiofrequency)partially depends upon the direction of contact between the electrodeand tissue. In particular, for endocardial catheter applications, thepoint of electrode-tissue contact is typically 150 cm away from thepoint of application of force applied by the operator (whether manual orautomated) of the catheter outside of the body. Coupled with the factthat a beating heart is a dynamically moving wall, this gives rise tosome functional and theoretical challenges such as ensuring that theelectrode is in sufficiently constant mechanical contact with themyocardial wall.

Catheter systems having sensor assemblies, such as those mounted on thecatheter shaft proximal to the electrode (or another component) orremotely in the handle set, leave the possibility, however small, ofobtaining false positive outcomes when detecting contact between theelectrode and the tissue. False positive outcomes may occur, forexample, when the distal portion of the catheter, and not the electrode,is in contact with the tissue. Such condition may arise during thecatheter manipulation in the heart when, for instance, the distalportion of the catheter is curled inward so much as to lose electrodecontact with the tissue, while the distal portion of the catheter is incontact with the tissue. When that happens, remotely placed sensors cangenerate signals due to the deflection of the catheter shaft, therebyfalsely indicating contact between the electrode and tissue.Accordingly, contact sensors coupled to the electrode and provided inthe distal tip of the catheter can, among other things, help reduce thepossibility of obtaining false positive outcomes when detecting contactbetween the electrode (or another component) and the tissue.

Force sensor configurations that address the foregoing issues have beenpreviously disclosed. In some embodiments, such force sensors include acoupler that couples the electrode with the catheter shaft. In thosecases, the sensitivity and the dynamic range of the force sensor dependupon the stiffness of the coupler. Furthermore, the sensitivity and thedynamic range depends upon the directional stiffness of the couplerrange of the force sensor because force is a vector (i.e. force has amagnitude and direction). Thus, for example, if the coupler is stifferin the axial direction than in the transverse direction, the forcesensor will have a wider dynamic range in the axial direction than inthe transverse direction, and will be more sensitive in the transversedirection than in the axial direction.

BRIEF SUMMARY OF INVENTION

For some applications, it is desirable to have a catheter system thatincludes distal tip sensors that detect changes in an interactivesurface provided by an electrode (or another structure). It is alsodesirable to provide a system which is insensitive to radiofrequency(RF) field, electromagnetic interference (EMI), and thermal effects.Furthermore, it is also desirable to have a system which minimizes falsepositives, is robust in construction and has a wide dynamic range. In anembodiment, the electrode may be subjected to a compressive force due tomechanical contact of the electrode surface with another body orsurface. The sensors coupled to the distal tip of the catheter using thecoupler assembly of the invention can be used to measure contact of anelectrode with a dynamically moving wall, such as a beating heart.

Coupler assemblies and methods are disclosed as the coupler assembliesmay be used with a catheter. In one embodiment, a coupler assemblyincludes a spherical linkage coupler or spherical linkage for acatheter. The coupler comprises a first cylinder portion for connectingto a structure, and a second cylinder portion for connecting to a distalend of a body of the catheter. The coupler also comprises a sphericallinkage including at least two link arms. Each of the two link arms areconnected on one end to the first cylinder portion and on the other endto the second cylinder portion. The two link arms connect a portion ofthe structure to the distal end of the catheter and enable the structureto move relative to the distal end of the catheter in response to anexternal force exerted on the structure.

In another embodiment, a catheter system comprises a body having aproximal end and a distal end, and a structure. The structure includes atip portion and a base portion, and a generally central axis. A couplerassembly is provided for connecting a portion of the structure to thedistal end of the catheter. The coupler assembly comprises a firstcylinder portion and a second cylinder portion. The coupler assemblyalso comprises a spherical linkage including two link arms. Each of thetwo link arms connected on one end to the first cylinder portion and onthe other end to the second cylinder portion.

For the coupler assembly described above, in an embodiment, the distalend of the catheter may include a coupling member having a neck portion.The neck portion of the coupling member, in an embodiment, may moverelative to an external force exerted on the structure. In anembodiment, the neck portion of the coupling member may include a twist,torsion bar, alpha, dove-tail or spring shaped elastic portion forenabling external axial and transverse forces and torques exerted on thestructure to be sensed by the sensor. The coupling member, in anembodiment, may include a mounting shaft that defines an internalrecessed groove for receiving at least a portion of the sensor. In anembodiment, the tip portion of the structure may include an irrigationport. The structure, in an embodiment, may include a lumen providedwithin an internal cavity of the structure, with the lumen beingpositioned adjacent to the base and tip portions of the structure.

For the coupler assembly described above, in an embodiment, a lumen maybe disposed within the body of the catheter, with at least a portion ofthe lumen extending into the structure for slidably receiving one ormore sensing components. In an embodiment, a lumen may be disposedwithin the body of the catheter, with at least a portion of the lumenextending into the structure for slidably receiving one or moreenergizing components. The energizing component may be a radiofrequencycurrent, direct current, high-intensity ultrasound, laser, cryogenic,chemical, electromagnetic radiation, and combinations thereof. In anembodiment, the tip portion of the structure may include a portionconfigured to perform ablation. The sensor, in an embodiment, may beadapted to measure a parameter, such as, intensity, wavelength, phase,spectrum, speed, optical path, interference, transmission, absorption,reflection, refraction, diffraction, polarization, and/or scattering.The coupler may also be used in conjunction with other sensors such as,electromechanical sensors, magnetic sensors, resistive sensors,inductive sensors, capacitive sensors, and quantum sensors, to name onlya few examples.

In another embodiment, a method for sensing contact force in a catheteris disclosed. The method comprises connecting a first cylinder portionto a structure, and connecting a second cylinder portion to a distal endof a body of the catheter. A spherical linkage is provided to connectthe first cylinder portion to the second cylinder portion so that thestructure moves relative to the distal end of the body of the catheterin response to an external force exerted on the structure. A sensor isprovided for the structure, the sensor sensing changes in intensity of asignal from the sensor responsive to displacement associated with thestructure in response to the contact force exerted by the structure on atissue.

For the method described above, in an embodiment, the structure mayperform RF ablation, HIFU ablation, laser ablation, cryogenic ablation,chemical ablation, radiation therapy, ultrasonic imaging, electricalpacing, EP pacing, electrical sensing, and/or EP sensing. In anembodiment, the sensed contact force may be utilized for automaticallylimiting a maximum contact force, warning of a high or unacceptablecontact force, giving visual or audible feedback to a practitionerregarding a tissue contact force, warning of a loss of contact force orcontact, and/or warning of a contact force which may be too low.

The foregoing and other aspects, features, details, utilities, andadvantages of the invention will be apparent from reading the followingdescription and claims, and from reviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a catheter assembly inaccordance with an embodiment of the invention.

FIG. 2 is an enlarged partial perspective view of the catheter assemblyshown in FIG. 1, wherein the electrode and portion of the sensingassembly is shown in phantom.

FIGS. 3 and 3A-3D show an exemplary embodiment of a coupler assemblywith compliant joints according to the invention.

FIGS. 4A-4D show an alternative exemplary embodiment of a couplerassembly similar to that shown in FIGS. 3A-3D, wherein the couplerassembly includes a stop surface and a displacement stop.

FIGS. 5 and 5A-5D show an alternative exemplary embodiment of a couplerassembly with revolute joints according to the invention.

FIG. 5E shows an alternative exemplary embodiment of a coupler assemblyaccording to the invention, similar to that shown in FIGS. 5A-5D buthaving a lip and stopper to form a “leaf spring” type configuration.

FIGS. 6A-6D show an alternative exemplary embodiment of a couplerassembly similar to that shown in FIGS. 5A-5D, wherein the couplerassembly includes a stop surface and a displacement stop.

FIGS. 7A-7B are exemplary views of the coupler assembly similar to thatshown in FIGS. 3A-3D as the coupler assembly may be fitted to acatheter.

FIGS. 8A-8B are exemplary views of the coupler assembly fitted to acatheter similar to that shown in FIG. 78 illustrating movement of thecoupler assembly relative to the catheter.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are usedto identify like components in the various views, FIGS. 1 and 2illustrate an exemplary embodiment of a contact sensing assembly 10which may implement a coupler assembly 50 of the invention (see, e.g.,FIGS. 3A-D). In a general form, the contact sensing assembly 10 includesa catheter 12, an electrode 14 connected to the catheter 12, and asensor 16 for interacting with a portion of electrode 14. The contactsensing assembly 10 may be used in the diagnosis, visualization, and/ortreatment of tissue (such as endocardial tissue) in a body. Contactsensing assembly 10 may be used in a number of diagnostic andtherapeutic applications, such as for example, the recording ofelectrograms in the heart, the performance of cardiac ablationprocedures, and/or various other applications. The catheter 12 can beused in connection with a number of applications that involve humans, orother mammals, for tissue observation, treatment, repair or otherprocedures. Moreover, the invention is not limited to one particularapplication, but rather may be employed by those of ordinary skill inthe art in any number of diagnostic and therapeutic applications. Forexample, the catheters disclosed herein may be usable in combinationwith a robotic system (e.g., disclosed in commonly owned and copendingapplications titled “Robotic Catheter System,” “Robotic CatheterManipulator Assembly,” “Robotic Catheter Device Cartridge,” “RoboticCatheter Rotatable Device Cartridge,” “Robotic Catheter Input Device,”“Robotic Catheter System Including Haptic Feedback,” and “RoboticCatheter System with Dynamic Response,” the respective disclosures ofwhich are incorporated herein by reference in their entirety), forexample, for coupling to a computer controlled catheter or surgicalinstrument for real-time feedback and precise control during aprocedure.

Catheter 12 of the invention includes a body 18 having a distal end 20and a proximal end 22. Body 18 of catheter 12 is generally tubular inshape, although other configurations of the catheter 12 may be used asknown in the industry. Distal end 20 of catheter 12 is connected toelectrode 14, while body 18 of catheter 12 may house sensor 16 and othercomponents used in the diagnosis and/or treatment of tissue. If desired,the outer portion of catheter 12 may have a braided outer coveringtherein providing increased flexibility and strength. The catheters ofthe invention vary in length and are attached to a handle or other typeof control member that allows a surgeon or operator of the catheter 12to manipulate the relative position of the catheter 12 within the bodyfrom a remote location, as recognized by one of ordinary skill in theart.

As generally shown in FIG. 1, an embodiment of the invention includesdistal end 20 of catheter 12 that includes at least a portion or segmentthat exhibits increased flexibility relative to more proximal portionsof the catheter 12. The increased flexibility of at least a portion orsegment associated with the distal end 20 may be achieved using thecoupler assembly 50 of the present invention (see, e.g., FIGS. 3A-D),which allows for increased flexibility at a portion or segment of thedistal end 20 of catheter 12.

Electrode 14 is connected to distal end 20 of catheter 12 by the couplerassembly 50 (see, e.g., FIGS. 3A-D). Upon the exertion of externalcontact force on the surface of electrode 14, at least a portion ofdistal end 20 of catheter 12 flexes and/or bends and/or compressesrelative to electrode 14 (see, e.g., FIGS. 8A-B). The relative movement(e.g., displacement either axially, laterally, compression, or acombination thereof) of distal end 20 may be proportionate or correlatedto the force exerted on electrode 14. The coupler assembly 50 will bedescribed in more detail below with reference to the remaining figures.

Electrode 14 includes a tip portion 24 and a base portion 26. Electrode14 may be configured to include a means for irrigating. For example,without limitation, the incorporation of at least one irrigation port 28within electrode 14, therein providing an irrigated electrode tip. Anirrigated electrode tip allows for the cooling of electrode 14, forinstance, through the transporting of fluid through electrode 14 andaround the surface of the tissue. A number of different types ofelectrodes, irrigated and non-irrigated, may be connected andincorporated for use with an electrode 14 according to embodiments ofthe invention depending on the type of procedures being done. Suchirrigated electrodes include, but are not limited to, those disclosed inU.S. patent application Ser. Nos. 11/434,220 (filed May 16, 2006),10/595,608 (filed Apr. 28, 2006), 11/646,270 (filed Dec. 28, 2006)11/647,346 (filed Dec. 29, 2006) and 60/828,955 (filed Oct. 10, 2006),each of which is hereby incorporated by reference as though fully setforth herein.

The catheter 12 may also include a sensing system. In one exemplaryembodiment where an optical sensor is implemented, electrode 14 mayinclude an optically interactive surface 30 on a portion of theelectrode 14 that interacts with the optical sensor 16. As shown in FIG.2, electrode 14 may further include an electrode cavity 36, as shown inphantom. Electrode cavity 36 may also be used to provide a number ofdifferent components and/or functions in connection with the electrode.In an embodiment, electrode cavity 36 may further provide the opticallyinteractive surface 30 therein enabling an optical sensor 16 to interactwith the internal surface of electrode 14 provided by electrode cavity36. In alternate embodiments, electrode cavity 36 may serve as a lumenfor transferring of irrigation channels, electrical components, or anyother type assembly components transferred through electrode 14.

In general, an optically interactive surface 30 may be provided on or inconnection with a surface associated with electrode 14, such that thesurface positioning, configuration, and orientation of the interactivesurface 30 (which has a know position with respect to the electrode)allows sufficient interaction and/or functional communication with theoptical sensor 16 such that a change in the communication (e.g., opticalsignal, light intensity) can provide a means for determining the contactforce and/or orientation of the electrode with the tissue or surroundingarea.

The optical sensor 16 may be positioned within the distal end 20 of thecatheter 12. The optical sensor 16 may include at least one optic fiberthat transmits and receives an optical signal, such as light energy. Theoptical sensor 16 may also be manufactured to transmit and/or receivevarious types of signals including those associated with electromagneticradiation, lasers, x-rays, radiofrequency, etc. In an embodiment,optical sensor 16 may use light energy to determine the relative contact(e.g., force, stress, and/or orientation) between electrode 14 and anexternal surface in operational contact with the electrode—for example,tissues and surrounding environments, including organs, heart chambers,and interior of vessels. In an embodiment, the optical sensor may beadapted to measure one or more parameters, including, for example,intensity, wavelength, phase, spectrum, speed, optical path,interference, transmission, absorption, reflection, refraction,diffraction, polarization, and scattering.

In an embodiment, one or more force vectors may be used to determine thecontact force and/or orientation of the electrode in connection with thesurrounding tissue or other external surfaces. In order to determinelight or optical intensity, optical sensor includes a receiver and anemitter for receiving and emitting light energy, respectively. Thereceiver and emitter may be included in a single fiber optic cable or intwo separate fiber optic cables, such as shown in FIG. 2. A number ofoptical sensors may be arranged within distal end 20 of catheter 12 tooperatively (e.g., optically) interact with an interactive surface thatis provided in connection with electrode 14. Moreover, a number ofreceivers and emitters may be disposed within distal end 20 of catheter12 in various configurations and combinations to assess contact and/ororientation readings. Such positioning and combinations can beconfigured adapted to optimize their operation for an intendedapplication or environment.

Exemplary embodiments of an optical sensor for use with catheters, suchas the catheter 10, are described in more detail in the '857application. Therefore, further discussion is not necessary herein inorder to fully practice the present invention. It should be noted,however, that the optical sensor described above is discussed forpurposes of illustration only and is merely one type of sensor that maybe implemented with the present invention. Other types of sensors mayalso be implemented, including but not limited to, capacitive,inductive, magnetic, electromagnetic, acoustic, piezoelectric, pressure,stress, strain, Wheatstone bridge-type, motion, resistive, and othertypes of sensors now known or later developed.

It is noted that at least one lumen is included in the catheter 12 forreceiving various energizing or sensing components. Exemplary sensingcomponents may include a thermal sensor, pressure sensor, tissue sensor,electrogram sensor, or other type of sensors and combinations thereofthat are known by those of ordinary skill in the art. An additionallumen may extend from catheter 12 through coupler assembly 50 and intoelectrode 14, therein providing an energizing component, such as sourcefor radiofrequency current, direct current, high-intensity ultrasound,laser, cryogenics, or other type of energizing component andcombinations that are known by those of ordinary skill in the art.Additional lumens may also be provided by assembly 10 for communicationwith additional components for the assembly, such as electricalcomponents, fluid (i.e. saline) passageways, or others known in theindustry.

It is also noted that electrode 14 may have alternate tip configurationsdepending on the type of procedure or use of the catheter 12. Aspreviously suggested, electrode 14 may be provided having an irrigatedelectrode tip or a non-irrigated electrode tip. Each of these may beused in connection with embodiments of the invention.

As generally illustrated in FIGS. 1 and 2, base portion 26 of electrode14 is connected to the catheter 12 via the coupling member 50. As tipportion 24 of electrode 14 is exposed to external force through contactwith tissue (e.g., as illustrated in FIGS. 8A-8B), the tip 24 ofelectrode 14 moves relative to the catheter body 18. In order tofacilitate this movement (e.g., bending, rotation, and compression) ofthe tip portion 24 of the catheter 12 during use, catheter 12 may befitted with a coupler assembly 50 in the distal end 20 of the catheter12.

FIGS. 3 and 3A-3D show an exemplary embodiment of a coupler assembly 50having a generally spherical operating configuration. FIG. 3 shows atop-plan view and FIGS. 3A-3D are perspective views. The couplerassembly 50 may include a first cylinder portion 51 for connecting to astructure (such as the electrode 14), and a second cylinder portion 52for connecting to the distal end 20 of a body 18 of the catheter 12. Thecoupler assembly 50 also includes a spherical linkage 60 including atleast two link arms 61 and 62.

Each of the two link arms 61 and 62 are connected on one end to thefirst cylinder portion 51 and on the other end to the second cylinderportion 52. In the embodiment shown in FIGS. 3A-3D, the link arms 61 and62 are formed with compliant joints 54 for joining the first cylinderportion 51 to the second cylinder portion 52. Two compliant joints 54are shown as semi-circular indentations at each end of both link arms 61and 62. Of course other configurations for providing compliant jointsare also contemplated.

The joint axes 55 a and 55 b of the spherical linkage intersect at thesame virtual center 55. In one embodiment, the virtual center 55 may beon the axis of the catheter, although any suitable axes may be used.Additionally, the virtual center 55 may be anywhere along the axis. Itis also noted that the angle formed between axes 55 a and 55 b may be 90degrees or any other suitable angle. Selection of the position ofvirtual center 55 and the angle between axes 55 a and 55 b may depend atleast in part on design considerations.

The distal end rotates about this virtual center 55 such that when aforce is applied to the first cylindrical portion 51 or a structure(such as the electrode 14) connected to the first cylindrical portion 51the resulting angular displacement is substantially equally responsiveto forces in the x-y plane. The force in z-direction is taken up by theflexure in the mechanism. Thus, this coupler separates forces in thetransverse and axial direction. The applied force can then be correlatedand calibrated with the angular displacement. Conversely, the calibratedangular displacement may be used to determine the applied force.

Furthermore, when a force is applied in the longitudinal or axial (z)direction to the first cylindrical portion 51 or a structure (such asthe electrode 14) connected to the first cylindrical portion 51, thespherical linkage and the compliance of the linkage (either in thejoints or in the link itself) in the axial (z) direction causesdisplacement along the axial (z) direction. This allows a compliance ora force/displacement sensor that can measure force given rotation abouttwo axes, such as the transverse axes (x, y) and displacement along oneaxis such as the longitudinal axis (z). Thus, this embodiment provides acompact design of three degrees-of-freedom force/displacement sensor ina very compact design. Such a sensor could be interchangeably used todetermine displacement from a measured force. Additionally, this designallows for the links to be confined to the peripheral solid portion ofthe cylinder and not interfere with the space within the catheterthereby leaving room for other components and other devices within thecatheter.

It will be understood by one of skill in this art that other joints maybe substituted for the revolute and compliant joints described here toobtain similar effects including sliders and cams.

The coupler assembly 50 may be manufactured as a single component. In anexemplary embodiment, a cylindrical section of tubing may be cut (e.g.,using a laser for micro-precision) in a threaded or “corkscrew”configuration, such that the cut tubing forms opposing cylinder portions51 and 52 connected to one another by link arms 61 and 62.

The spherical linkage may be manufactured of a variety of differentmaterials to provide for different elastic properties based on specificcatheter uses. The coupler assembly 50 and components thereof may bedesigned so that the movement of an electrode 14 attached to the couplerassembly 50 has a uniform response in the generally x, y and zdirections of a force and/or torque applied to the electrode formeasurement by the contact sensing assemblies disclosed herein.

It can readily be seen in FIGS. 3B-3D how the spherical operatingconfiguration of the coupler assembly 50 enables motion about therotational axis such that the motion in the transverse direction (x, y)is controlled by the spherical mechanism and the translation in theaxial direction (z) depends on the compliance of the coupler and theclearance in the linkage. Accordingly, the coupler assembly 50 enablescontrolled movement in response to external bending or rotationalpressure on one of the cylinder portions, e.g., as illustrated by arrow71 in FIG. 3B and arrow 72 in FIG. 3C. The coupler assembly 50 is alsoresponsive to external compressive pressure, e.g., as illustrated byarrows 73 a-b in FIG. 3D. In each of these figures, motion of the firstcylinder portion 51 is shown relative to the second cylinder portion 52.

FIGS. 4A-4D show an alternative exemplary embodiment of a couplerassembly 150 similar to that shown in FIGS. 3A-3D. It is noted that100-series reference numbers identify similar components to thosealready described above for FIGS. 3A-3D and therefore may not bedescribed again with reference to FIGS. 4A-D for sake of clarity.

The coupler assembly 150 includes a displacement stop 170 a and 170 bfor each link arm 161 and 162, respectively. In operation, thedisplacement stops 170 a and 170 b cooperates with a stop surface (e.g.,on the link arm 161 and 162, respectively) to limit compression of theelectrode 14 in a direction toward the catheter 12, as illustrated byarrows 173 a and 1731), and controls or limits the stress of the arms inthis configuration. It can be seen in FIGS. 4C-4D, however, that thedisplacement stops 170 a and 170 b do not interfere with or otherwiselimit rotational movement of the electrode 14, as illustrated by arrow171 in FIG. 4C and arrow 172 in FIG. 4D.

FIGS. 5 and 5A-5D show an alternative exemplary embodiment of a couplerassembly 250 according to the invention, similar to that shown in FIGS.3 and 3A-3D but having revolute joints instead of compliant joints.Again. FIG. 5 shows a top-plan view and FIGS. 5A-5D are perspectiveviews. It is noted that 200-series reference numbers identify similarcomponents to those already described above for FIGS. 3A-3D andtherefore may not be described again with reference to FIGS. 5A-D forsake of clarity.

The coupler assembly 250 again includes a first cylinder portion 251 forconnecting to a structure (such as the electrode 14), and a secondcylinder portion 252 for connecting to the distal end 20 of a body 18 ofthe catheter 12. The coupler assembly 250 also includes a sphericallinkage 260 including at least two link arms 261 and 262.

Each of the two link arms 261 and 262 are connected on one end to thefirst cylinder portion 251 and on the other end to the second cylinderportion 252. In the embodiment of the coupler assembly 250 shown inFIGS. 5A-5D, however, the link arms 261 and 262 are attached withrevolute joints 254 (e.g., pins) for joining the first cylinder portion251 to the second cylinder portion 252. In this embodiment, the couplerassembly 250 is manufactured from multiple, separate components.

The joint axes 255 a and 255 b of the spherical linkage intersect at thesame virtual center 255. In one embodiment, the virtual center 255 maybe on the axis of the catheter, although any suitable axes may be used.Additionally, the virtual center 255 may be anywhere along the axis. Itis also noted that the angle formed between axes 255 a and 255 b may be90 degrees or any other suitable angle based. Selection of the positionof virtual center 255 and the angle between axes 255 a and 255 b maydepend at least in part on design considerations.

The distal end rotates about this virtual center 255 such that when aforce is applied to the first cylindrical portion 251 or a structure(such as the electrode 14) connected to the first cylindrical portion251 the resulting angular displacement is substantially equallyresponsive to forces in the x-y plane. The force in z-direction is takenup by the flexure in the mechanism. Thus, this coupler separates forcesin the transverse and axial direction. The applied force can then becorrelated and calibrated with the angular displacement. Conversely, thecalibrated angular displacement may be used to determine the appliedforce.

It can readily be seen in FIGS. 5B-5D how the spherical operatingconfiguration of the coupler assembly 250 with revolute joints alsoenables motion about the rotational axis such that the motion in thetransverse direction (x, y) is controlled by the spherical mechanism andthe translation in the axial direction (z) depends on the compliance ofthe coupler and the clearance in the linkage. Accordingly, the couplerassembly 250 enables controlled movement in response to external bendingor rotational pressure on one of the cylinder portions, e.g., asillustrated by arrow 271 in FIG. 5B and arrow 272 in FIG. 5C. Thecoupler assembly 250 is also responsive to external compressivepressure, e.g., as illustrated by arrows 273 a-b in FIG. 5D. In each ofthese figures, motion of the first cylinder portion 251 is shownrelative to the second cylinder portion 252.

FIG. 5E shows an alternative exemplary embodiment of a coupler assemblyaccording to the invention, similar to that shown in FIGS. 5A-5D buthaving a lip and stopper to form a “leaf spring” type configuration.Such an embodiment aids in the elasticity of the joints and allows thejoints to readily spring back to a preconfigured orientation.

FIGS. 6A-6D show an alternative exemplary embodiment of a couplerassembly similar to that shown in FIGS. 5A-5D, wherein the couplerassembly includes a stop surface and a displacement stop. It is notedthat 300-series reference numbers identify similar components to thosealready described above for FIGS. 3A-3D and therefore may not bedescribed again with reference to FIGS. 6A-D for sake of clarity.

The coupler assembly 350 includes a displacement stop 370 a and 370 bfor each link arm 361 and 362, respectively. In operation, thedisplacement stops 370 a and 370 b cooperates with a stop surface (e.g.,on the link arm 361 and 362, respectively) to limit compression of theelectrode 14 in a direction toward the catheter 12, as illustrated byarrows 373 a and 373 b. It can be seen in FIGS. 6C-6D, however, that thedisplacement stops 370 a and 370 b do not interfere with or otherwiselimit rotational movement of the electrode 14, as illustrated by arrow371 in FIG. 6C and arrow 372 in FIG. 6D.

FIGS. 7A-7B are exemplary views of the coupler assembly similar to thatshown in FIGS. 3A-3D as the coupler assembly 50 may be fitted to acatheter. For example, the coupler assembly 50 may be connected on thebase or second cylinder portion 52 to the catheter 12 (e.g., bythreading, snap, or other connection) and moved in the direction ofarrow 90 into connection with the electrode 14 (e.g., again bythreading, snap, or other connection). A catheter tubing or sheath 95may then be slid over the internal components of the catheter 12 and thecoupler assembly 50.

FIGS. 8A-8B are exemplary views of the coupler assembly fitted to acatheter similar to that shown in FIG. 7B illustrating movement of thecoupler assembly relative to the catheter. In operation, with couplerassembly 50 installed onto a base portion of the electrode 14, anyaxial, transverse or otherwise rotational forces, and/or compressiveforces applied to electrode 14 when contacting a membrane or othersurface may result in controlled deformation of portion 20 of thecatheter 12. The resulting deformation may directly correlate to theaxial, transverse or otherwise rotational forces applied to electrode14, with the forces and angle of rotation being calculated depending onthe type of sensor being implemented.

The invention further contemplates use of the catheter 12 with a systemthat includes assembly 10 of the invention connected to a signalconverter (not shown), such as an analog to digital converter or othersuitable signal processing capability, and an operator interface, whichmay further include a computer and display (also not shown), forprocessing the signals received from assembly 10 in connection withpositioning and contact with tissue, such as myocardial tissue. Thisinformation is processed to determine the contact force exerted onelectrode 14 of assembly 10. A calibration system (not shown), e.g.,implemented in software, may be further provided to correlate theamplitude or intensity of the received signal to the external force onthe electrode. A mapping system, such as the Ensite system, also knownas NavX®, may be integrated with the system to provide a visualizationand mapping system for use in connection with assembly 10 of theinvention. In an alternate embodiment, the signal processor may beintegrated with each of the receivers provided by the sensor(s), suchthat the signal is directly processed and provided on the operatorinterface. Overall, each of these components may be modified and/orintegrated with one another depending on the design of the opticalsystem as recognized by one of ordinary skill in the art.

As previously described, the invention provides a method of sensingcontact force and/or orientation as provided by the contact sensingassembly and system. The signals may be correlated to, among otherthings, force vectors exerted by the electrode on an adjacent tissue.

EXAMPLES

The following are examples of other embodiments which are contemplated,and are provided for purposes of illustration, but are not intended tobe limiting in any manner.

A spherical linkage coupler for a catheter, comprising: a first cylinderportion for connecting to a structure; a second cylinder portion forconnecting to a distal end of a body of the catheter; a sphericallinkage including at least two link arms, wherein each of the at leasttwo link arms is connected on one end to the first cylinder portion andon the other end to the second cylinder portion, thereby connecting aportion of the structure to the distal end of the catheter and enablingthe structure to move relative to the distal end of the catheter inresponse to an external force exerted on the structure.

The coupler, wherein the spherical linkage is configured to enablerotation of the structure relative to the body of the catheter.

The coupler, wherein the spherical linkage is configured to enablecompression of the structure toward the body of the catheter.

The coupler, wherein the at least two link arms are connected to thefirst and second cylinder portions by revolute joints.

The coupler, wherein the at least two link arms are connected to thefirst and second cylinder portions by compliant joints.

The coupler, further comprising: at least one stop surface; and at leastone displacement stop, the displacement stop cooperating with the stopsurface to limit compression of the structure toward the body of thecatheter.

The coupler, wherein the at least two link arms include compliantjoints.

The coupler, wherein at least one sensor is operatively connected to oneof the structure and the catheter body.

The coupler, wherein the spherical linkage is configured to enableexternal axial and transverse forces and torques exerted on thestructure to be sensed by the at least one sensor.

A method for sensing contact force in a catheter, comprising: connectinga first cylinder portion to a structure: connecting a second cylinderportion to a distal end of a body of the catheter; providing a sphericallinkage to connect the first cylinder portion to the second cylinderportion so that the structure moves relative to the distal end of thebody of the catheter in response to an external force exerted on thestructure; providing a sensor for the structure.

The method, wherein the structure senses changes in intensity of asignal from the sensor responsive to displacement associated with thestructure in response to the contact force exerted by the structure on atissue.

The method, wherein the structure performs one of RF ablation, HIFUablation, laser ablation, cryogenic ablation, chemical ablation,radiation therapy, ultrasonic imaging, electrical pacing. EP pacing,electrical sensing, and EP sensing.

The method, further comprising determining the axial and transversecomponents of contact force as a function of an angle of attack of thestructure relative to the tissue.

The method, further comprising using a calibrated sensor to determineaxial and transverse components of the contact force.

The method, further comprising determining the contact force magnitudeas a function of the axial and transverse components of the contactforce.

The method, further comprising determining an angle of attack of thestructure relative to the tissue as a function of the axial andtransverse components of the contact force.

The method, further comprising determining an angle of rotation of thestructure relative to the tissue as a function of the change inintensity and phase angle of the sensor.

Although a number of embodiments of this invention have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this invention. For example, alljoinder references (e.g., attached, coupled, connected, and the like)are to be construed broadly and may include intermediate members betweena connection of elements and relative movement between elements. Assuch, joinder references do not necessarily infer that two elements aredirectly connected and in fixed relation to each other. It is intendedthat all matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative only and notlimiting. Changes in detail or structure may be made without departingfrom the spirit of the invention as defined in the appended claims.

1. A catheter system comprising: a body having a proximal end and adistal end; a structure including a tip portion and a base portion, anda generally central axis; a coupler assembly connecting a portion of thestructure to the distal end of the catheter, the coupler assemblycomprising: a first cylinder portion and a second cylinder portion; anda spherical linkage including at least two link arms, wherein each ofthe at least two link arms is connected on one end to the first cylinderportion and on the other end to the second cylinder portion.
 2. Thecatheter system according to claim 1, wherein joint axes of thespherical linkage intersect at the same virtual center.
 3. The cathetersystem according to claim 2, wherein the virtual center is on the axisof the catheter.
 4. The catheter system according to claim 1, whereinthe coupler assembly is configured to enable rotation of the structurerelative to the body of the catheter.
 5. The catheter system accordingto claim 1, wherein the coupler assembly is configured to enablecompression of the structure toward the body of the catheter.
 6. Thecatheter system according to claim 1, wherein the two link arms areconnected to the first and second cylinder portions by resolute joints.7. The catheter system according to claim 1, wherein the two link armsare connected to the first and second cylinder portions by compliantjoints.
 8. The catheter system according to claim 1, wherein the couplerassembly further includes a stop surface and a displacement stop foreach of the two link arms, the displacement stop cooperating with thestop surface to limit compression of the structure toward the body ofthe catheter.
 9. The catheter system according to claim 1, wherein thestructure is an electrode.
 10. The catheter system according to claim 1,wherein the coupler assembly moves relative to an external force exertedon the structure.
 11. The catheter system according to claim 1, whereinthe tip portion of the structure includes an irrigation port.
 12. Thecatheter system according to claim 1, wherein the structure includes alumen provided within an internal cavity of the structure, the lumenbeing positioned adjacent to the base and tip portions of the structure.13. The catheter system according to claim 1, further comprising a lumendisposed within the body of the catheter, at least a portion of thelumen extending into the structure for slidably receiving at least onesensing component.
 14. The catheter system according to claim 1, whereinthe tip portion of the structure includes a portion configured toperform ablation.
 15. The catheter system according to claim 1, furthercomprising a lumen disposed within the body of the catheter, at least aportion of the lumen extending into the structure for slidably receivingat least one energizing component.
 16. The catheter system according toclaim 15, wherein the energizing component is selected from aradiofrequency current, direct current, high-intensity ultrasound,laser, cryogenic, chemical, electromagnetic radiation, and combinationsthereof.
 17. The catheter system according to claim 1, furthercomprising at least one sensor being operatively connected to one of thestructure and the catheter body.
 18. The catheter system according toclaim 17, wherein the coupler assembly is configured to enable externalaxial and transverse forces and torques exerted on the structure to besensed by the at least one sensor.
 19. The catheter system according toclaim 17, wherein the sensor is one of the following: an optical sensoradapted to measure a parameter selected from the group consisting ofintensity, wavelength, phase, spectrum, speed, optical path,interference, transmission, absorption, reflection, refraction,diffraction, polarization, and scattering; or selected from the groupconsisting of: capacitive, inductive, magnetic, electromagnetic,acoustic, piezoelectric, pressure, stress, strain, Wheatstonebridge-type, motion, and resistive.
 20. The catheter system according toclaim 17, further comprising a system operatively associated with thesensor to determine a displacement associated with the structure usingsensed changes in intensity of a signal from the at least one sensor.